Causes Of Trends Research Articles

Trends in vegetation NDVI from 1 km AVHRR data over Canada for the period 1985–2006

Long‐term changes in the Normalized Difference Vegetation Index (NDVI) have been evaluated in several studies but results have not been conclusive due to differences in data processing as well as the length and time of the analysed period. In this research a newly developed 1 km Advanced Very High Resolution Radiometer (AVHRR) satellite data record for the period 1985–2006 was used to rigorously evaluate NDVI trends over Canada. Furthermore, climate and land cover change as potential causes of observed trends were evaluated in eight sample regions. The AVHRR record was generated using improved geolocation, cloud screening, correction for sun‐sensor viewing geometry, atmospheric correction, and compositing. Results from both AVHRR and Landsat revealed an increasing NDVI trend over northern regions where comparison was possible. Overall, 22% of the vegetated area in Canada was found to have a positive NDVI trend based on the Mann–Kendal test at the 95% confidence level. Of these, 40% were in northern ecozones. The mean absolute difference of NDVI measurements between AVHRR and Landsat data was <7%. When compared with results from other studies, similar trends were found over northern areas, while in southern regions the results were less consistent. Local assessment of potential causes of trends in each region revealed a stronger influence of climate in the north compared to the south. Southern regions with strong positive trends appeared to be most influenced by land cover change.

Changing trends in causes and patterns of facial fractures in children

To review the epidemiology of facial fractures in children and to analyze whether it has changed over time. Retrospective review of records of children aged < or = 15 years diagnosed for fracture during 2 10-year periods. A total of 378 children were diagnosed with fractures, 187 in 1980-1989 and 191 in 1993-2002. The proportion of children with mandibular fractures decreased by 13.6 percentage-points from the first period to the second, whereas the proportion of patients with midfacial fractures increased by 18.7 percentage-points. Assault as a causative factor increased by 5.5 percentage-points, almost exclusively among children aged 13-15 years, with a high percentage (23.5%). Recognition of a change in fracture patterns over time is probably due to the increased use of computerized tomographic scanning.

Which women stop at one child in Australia?

The decline in fertility in Australia in the 1990s reflected both decreased first-order birth rates and decreased second-order birth rates (Kippen 2004). Whilst childlessness has been studied extensively, little attention has been paid to the progression from one to two children. This study analyses which women stop at one child using data from 1,809 parous 40–54 year olds from Wave 1 of the Household Income and Labour Dynamics in Australia (HILDA) survey. Important early lifecourse predictors of whether a woman stops her childbearing at one child are shown to be a woman s country of birth, highest level and type of schooling, and her father s occupation. A woman s marital status and her age at the time of the first birth are also shown to be significant predictors of her likelihood of not progressing to a second birth. The causes of trends over time are discussed.

Nature and causes of trends in male diabetes prevalence, undiagnosed diabetes, and the socioeconomic status health gradient

This paper investigates levels in diabetes prevalence patterns across key socioeconomic status indicators and how they changed over time. The investigation spans both the conventional concept of diagnosed diabetes and a more comprehensive measure that includes those whose diabetes is undiagnosed. By doing so, I separate the distinct impact of covariates on trends over time in disease onset and the probability of disease diagnosis. The principal force leading to higher diabetes prevalence over time is excessive weight and obesity, which was only partially offset by improvements in the education of the population over time. Undiagnosed diabetes remains an important health problem, but much less so than 25 years ago. Although race and ethnic differentials in undiagnosed diabetes were eliminated over the last 25 years, the disparities became larger across other measures of disadvantage, such as education.

Wind Run Changes: The Dominant Factor Affecting Pan Evaporation Trends in Australia

AbstractThe Class A pan evaporation rates at many Australian observing stations have reportedly decreased between 1970 and 2002. That pan evaporation rates have decreased at the same time that temperatures have increased has become known as the “pan evaporation paradox.”Pan evaporation is primarily dependant on relative humidity, solar radiation, and wind. In this paper, trends in observed pan evaporation in Australia during the period 1975–2004 were attributed to changes in other climate variables using a Penman-style pan evaporation model. Trends in daily average wind speed (termed wind run) were found to be an important cause of trends in pan evaporation. This result is a significant step toward resolving the pan evaporation paradox for Australia.Data inspection and interstation comparison revealed that some of the significant wind run trends were discontinuous or spatially uncorrelated. These analyses raised the possibility that some of the changes in observed wind run, and by implication some of the significant changes in pan evaporation, may represent changes in the local environment surrounding the observing stations.Daily pressure gradients and NCEP–NCAR reanalysis wind surfaces were analyzed in an attempt to identify any climatological wind run trends associated with large-scale changes in atmospheric circulations. Unfortunately, the trends from the two data sources were not consistent, and the challenge remains to conclusively identify the cause or causes of the changes in observed station wind run in Australia.

Analysis of Construction Worker Injuries That Do Not Result in Lost Time

Attempts to examine the root causes of injuries in the construction industry have been largely focused on fatalities and other serious injuries. These efforts were undertaken with the assumption that the root causes of serious injuries could lead to identifying approaches that could prevent the recurrence of similar injuries in the future and that these approaches would also be successful in eliminating many minor injuries. While some injuries may be either minor or serious depending on small differences in worker position, etc., that assumption does not appear to be valid for most injuries. The trends of causes leading to minor injuries are often quite different from those resulting in serious injuries. With this assumption, an examination was conducted to profile nearly 136,000 construction worker injuries, most of which did not result in lost time. Results indicate that these injuries, not resulting in lost time, generally do not fit the profile of injuries that result in fatalities or that are serious. Over half of the injuries in the present study were associated with lacerations (usually of the fingers and hand) and injuries sustained by the lumbar spine, upper extremities, or eyes. The percentage of injuries that involved lacerations was considerably higher for construction than for all other industries. The costs of injuries were found to be quite varied, depending on the part of the body that was injured.

Divergent trends in maternal cigarette smoking during pregnancy: United States 1990–99

While examination of causes for trends in smoking have largely focused on how changes have occurred with maternal age and, less commonly, time period, little is known as to how age, period and birth cohort interact on trends in the prevalence of smoking during pregnancy. We performed a population-based, retrospective cohort study based on the vital statistics records comprised of White (n=24,499,629) and Black (n = 5,096,625) women delivering in the United States in 1990-99. Smoking prevalence rates were derived by seven 5-year maternal age groups (15-19 to 45-49 years), two time periods (1990-94 and 1995-99), and eight 5-year maternal birth cohorts (1945-49 to 1980-84) after adjusting for the confounding effects of gravidity, education, marital status, and lack of prenatal care through multivariable logistic regression models. The prevalence of smoking was 17.3% among Whites, and 13.5% among Blacks, with substantial variations by age, time period, and birth cohort. The rate declined with increasing age among Whites during the 1990-94 and 1995-99 periods. Among Blacks, the rates increased steeply with advancing age up to 25-29 years and began to decline thereafter. Smoking rates declined among both Whites and Blacks with increasing birth cohort within each age strata. These rates were highest among multigravid women (gravida > or = 2), and lowest among primigravid women. The rates among Whites declined with increasing maternal age for each gravida. Among Blacks, smoking rates for each gravida increased with advancing age up to 25-29 years, and plateaued among older women. Variation in smoking prevalence by age, time period, and birth cohort provides impetus for designing interventions to reduce smoking. Such studies should not only consider cross-sectional trends, but also the divergent patterns by age and cohort among women of different race/ethnic groups and gravidity.

Recent Trends in Ethnic and Racial Business Ownership

Using Current Population Survey (CPS) microdata, I examine trends and the causes of the trends from 1979 to 1998 in business ownership among several ethnic/racial groups in the United States. I find rapid growth rates for the number of self-employed blacks, Hispanics, Asians and Native Americans relative to whites over the past decade or two. I find that the rapid growth rates were primarily due to expansions in the labor force for these groups. With the exception of female rates in the 1980s, trends in business ownership rates were fairly flat over the past two decades. There were, however, important differences across groups in changes in self-employment rates over the past decade or two. I use a dynamic decomposition technique to explore the causes of these differential trends and find some interesting patterns. For example, I find that increasing levels of education and relative declines in the age distribution of the workforce for some minority groups contributed to increasing racial gaps in self-employment.

Sibling Influence on Smoking Behavior: A Within‐Family Look at Explanations for a Birth‐Order Effect

Using a repeated‐measures design, we found a significant birth‐order relationship suggesting lower ages of smoking onset in later born siblings of a 1979 National Longitudinal Survey of Youth cohort. Two social learning mechanisms, modeling and opportunity, were explored to help illuminate the causes of trends in the within‐family means. When empirical patterns were compared to predictions derived from our specifications of how opportunity and modeling processes should work, the results were unsuccessful in explaining the birth‐order effect. As a third explanation of the birth‐order effect, telescoping did show a significant influence. The effect size was small, however, and had little effect on the group means assessed. Finally, a pattern did emerge that was consistent with a reformulation of the opportunity process in which sisters play a particularly strong role. We develop future research implications of this pattern and speculate on genetic and social conservatism explanations.

Analysis of 1970–1995 trends in tropospheric ozone at Northern Hemisphere midlatitudes with the GEOS‐CHEM model

The causes of trends in tropospheric ozone at Northern Hemisphere midlatitudes from 1970 to 1995 are investigated with the GEOS‐CHEM model, a global three‐dimensional model of the troposphere driven by assimilated meteorological observations from the Goddard Earth Observing System (GEOS). This model is used to investigate the sensitivity of tropospheric ozone with respect to (1) changes in the anthropogenic emission of nitrogen oxides and nonmethane hydrocarbons, (2) increases in methane concentrations, (3) variations in the stratospheric source of ozone, (4) changes in solar radiation resulting from stratospheric ozone depletion, and (5) increases in tropospheric temperatures. Model results indicate that local increases in NOx emissions have caused most of the increases seen in lower tropospheric ozone over Europe and Japan. Increases in methane are responsible for roughly one fifth of the anthropogenically induced increase in tropospheric ozone at northern midlatitudes. However, changes in ozone precursors do not adequately explain either the spatial differences in observed ozone trends across midlatitudes or the observed decreases in ozone over Canada throughout the troposphere. We argue that ozone depletion in the lowermost stratosphere is likely to have reduced the stratospheric source by as much as 30% from the early 1970s to the mid 1990s. Model simulations that account for such a reduction along with reported changes in anthropogenic emissions show steep declines of ozone in the upper troposphere and variable increases in the lower troposphere that are more consistent with observations. Differential temperature trends in summer between North America and Europe may account for at least some of the remaining spatial variation in tropospheric ozone trends. Increases in ultraviolet (UV) radiation due to stratospheric ozone depletion do not appear to significantly reduce tropospheric ozone, except at midlatitudes in the Southern Hemisphere following the breakup of the ozone hole.

Patterns of mortality in southern sea otters (Enhydra lutris nereis) from 1998-2001.

Detailed postmortem examination of southern sea otters (Enhydra lutris nereis) found along the California (USA) coast has provided an exceptional opportunity to understand factors influencing survival in this threatened marine mammal species. In order to evaluate recent trends in causes of mortality, the demographic and geographic distribution of causes of death in freshly deceased beachcast sea otters necropsied from 1998-2001 were evaluated. Protozoal encephalitis, acanthocephalan-related disease, shark attack, and cardiac disease were identified as common causes of death in sea otters examined. While infection with acanthocephalan parasites was more likely to cause death in juvenile otters, Toxoplasma gondii encephalitis, shark attack, and cardiac disease were more common in prime-aged adult otters. Cardiac disease is a newly recognized cause of mortality in sea otters and T. gondii encephalitis was significantly associated with this condition. Otters with fatal shark bites were over three times more likely to have pre-existing T. gondii encephalitis suggesting that shark attack, which is a long-recognized source of mortality in otters, may be coupled with a recently recognized disease in otters. Spatial clusters of cause-specific mortality were detected for T. gondii encephalitis (in Estero Bay), acanthocephalan peritonitis (in southern Monterey Bay), and shark attack (from Santa Cruz to Point Año Nuevo). Diseases caused by parasites, bacteria, or fungi and diseases without a specified etiology were the primary cause of death in 63.8% of otters examined. Parasitic disease alone caused death in 38.1% of otters examined. This pattern of mortality, observed predominantly in juvenile and prime-aged adult southern sea otters, has negative implications for the overall health and recovery of this population.

Evolving trends in risk profiles and causes of death after heart transplantation: A ten-year multi-institutional study

Background: As therapeutic options evolve for advanced heart failure, the appropriate role for cardiac transplantation will require survival analyses that reflect changing trends in causes of death and patient and institutional risk profiles. Results from multi-institutional studies could be used to monitor progress in individual centers. Methods: Between 1990 and 1999, 7290 patients undergoing cardiac transplantation in 42 institutions entered a formal outcomes study. Changing survival, causes of death, and patient risk profiles were analyzed. Multivariable risk-factor equations were applied to a single institution (300 primary heart transplants) to examine differences in risk-adjusted expected versus observed actuarial outcomes over time. Results: Overall survival in the 42 institutions improved during the decade (P =.02). One- and 3-year cardiac transplant research database survival was as follows: era 1 (1990-1992), 84% and 76%, respectively; era 2 (1993-1995), 85% and 79%, respectively; and era 3 (1996-1999), 85% and 79%, respectively. Causes of death changed over time. Pretransplantation risk profiles increased over time (P =.0001), with increases in reoperations, devices, diabetes, severely ill recipients, pulmonary vascular resistance, sensitization, ischemic times, donor age, and donor inotropic support. Three-year actuarial survival in a single institution was 3% less than risk-adjusted predicted survival in era 1, 1% higher than predicted in era 2, and 7% higher than predicted in era 3. Conclusions: Survival after cardiac transplantation is gradually improving, despite increasing risk profiles. Further improvement requires periodic re-evaluation of risk profiles and causes of death to target areas of surveillance, therapy, and research. By using these methods, progress at individual institutions can be assessed in a time-related, risk-adjusted manner that also reflects changing institutional experience, expertise, or both.J Thorac Cardiovasc Surg 2003;125:881-90

LONG-TERM DECLINES AND DECADAL PATTERNS IN POPULATION TRENDS OF SONGBIRDS IN WESTERN NORTH AMERICA, 1979–1999

Abstract We analyzed population trends from a constant-effort mist-netting study conducted in central coastal California during the autumns of 1979–1999. Of 31 taxa captured in sufficient numbers, 16 underwent statistically significant declines and none increased. Twice as many species declined from 1989–1999 as compared to 1979–1989. Overall, our results were similar to those of regional Breeding Bird Surveys determined for the same species during the same period. In an attempt to identify possible causes for trends, we grouped species by various life-history categories including nest height, nest type, likelihood of cowbird parasitism, wintering location, winter food preference, and tolerance for human presence on the breeding grounds. All groups underwent significant declines, although high nesters, common cowbird hosts, and Neotropical migrants declined faster than their respective counterparts. While life-history attributes explained differences in trends between groups, there was significant heterog...

Trends in water quality in LEASEQ rivers and streams (northwestern Ohio), 1975-1995. Lake Erie Agricultural Systems for Environmental Quality.

Trends in water quality in four northwest Ohio rivers over the period 1975-1995 were identified using datasets of daily concentrations containing 4500 to 6800 observations per river during the study period. Concentrations were log-transformed prior to analysis, and adjusted for flow using a locally weighted scatterplot smoother (LOWESS) fit between log(concentration) and log(flow). Seasonality was modeled using one- and two-cycle sinusoidal oscillations and monthly additive constants. Substantial decreases in total and soluble reactive phosphorus were documented at all stations. Smaller but highly significant decreases in total Kjeldahl nitrogen were documented at all stations, and significant decreases in total suspended solids were documented at three of the four stations. Nitrate did not show significant trends at the two stations draining major watersheds, and showed significant trends in opposite directions at the two stations on smaller watersheds. Comparisons using nonparametric, nonlinear trend fits (LOWESS) suggest that changes in fertilizer and manure application rates are the most important cause of trends in phosphorus and total Kjeldahl nitrogen; point sources are insufficient to account for the phosphorus trends. The conflicting trends for nitrate are enigmatic, but may reflect diverging land use in the two smaller watersheds.

Thirty-Year Bird Population Trends in an Unfragmented Temperate Deciduous Forest: Importance of Habitat Change

AbstractAbundances of forest birds in an unfragmented, undisturbed, and relatively mature temperate deciduous forest at the Hubbard Brook Experimental Forest, New Hampshire, changed markedly between 1969 and 1998. Total numbers of birds (all species combined) declined from 210–220 individuals/10 ha in the early 1970s to 70–90/10 ha in the 1990s. Of the 24 regularly occurring species, 12 decreased significantly (four to local extinction), three increased significantly, and nine remained relatively constant in abundance. Nine of the 12 declining species were Neotropical migrants. Most species exhibited similar trends on Breeding Bird Survey (BBS) routes in New Hampshire during the same 30 year period and on three replicate study sites in nearby sections of the White Mountains from 1986–1998. Probable causes of trends were diverse and differed among species. Most could be accounted for by individual species' responses to events occurring primarily in the local breeding area. The most important local factor affecting bird abundance was temporal change in forest vegetation structure, resulting from natural forest succession and local disturbances. Four species that declined markedly and in some cases disappeared completely from the study plot (Least Flycatcher, Empidonax minimus; Wood Thrush, Hylocichla mustelina; Philadelphia Vireo, Vireo philadelphicus; and American Redstart, Setophaga ruticilla) appear to attain peak abundance in early or mid successional forests. Species preferring more mature forests, such as Black-throated Green Warbler (Dendroica virens) and Ovenbird (Seiurus aurocapillus), increased significantly in abundance over the 30 year study. Other important factors influencing bird abundances were food availability and events in the migratory and winter periods. Nest-predation rates, although varying among years, showed no long-term pattern that would account for population declines, and brood parasites were absent from this forest. Findings from this study demonstrate that major changes in bird abundances occur over time even in undisturbed and relatively mature forests, and illustrate the need for considering habitat requirements of individual species and how habitat suitability changes over time when trying to assess the causes of their long-term population trends. The results also imply that any conclusions about the effects of other factors affecting forest bird abundances, such as increased nest predation or brood parasitism associated with habitat fragmentation, must also account for successional changes that may be affecting habitat suitability.

Thirty-Year Bird Population Trends in an Unfragmented Temperate Deciduous Forest: Importance of Habitat Change

Abundances of forest birds in an unfragmented, undisturbed, and relatively mature temperate deciduous forest at the Hubbard Brook Experimental Forest, New Hampshire, changed markedly between 1969 and 1998. Total numbers of birds (all species combined) declined from 210–220 individuals/10 ha in the early 1970s to 70–90/10 ha in the 1990s. Of the 24 regularly occurring species, 12 decreased significantly (four to local extinction), three increased significantly, and nine remained relatively constant in abundance. Nine of the 12 declining species were Neotropical migrants. Most species exhibited similar trends on Breeding Bird Survey (BBS) routes in New Hampshire during the same 30 year period and on three replicate study sites in nearby sections of the White Mountains from 1986–1998. Probable causes of trends were diverse and differed among species. Most could be accounted for by individual species' responses to events occurring primarily in the local breeding area. The most important local factor affecting bird abundance was temporal change in forest vegetation structure, resulting from natural forest succession and local disturbances. Four species that declined markedly and in some cases disappeared completely from the study plot (Least Flycatcher, Empidonax minimus; Wood Thrush, Hylocichla mustelina; Philadelphia Vireo, Vireo philadelphicus; and American Redstart, Setophaga ruticilla) appear to attain peak abundance in early or mid successional forests. Species preferring more mature forests, such as Black-throated Green Warbler (Dendroica virens) and Ovenbird (Seiurus aurocapillus), increased significantly in abundance over the 30 year study. Other important factors influencing bird abundances were food availability and events in the migratory and winter periods. Nest-predation rates, although varying among years, showed no long-term pattern that would account for population declines, and brood parasites were absent from this forest. Findings from this study demonstrate that major changes in bird abundances occur over time even in undisturbed and relatively mature forests, and illustrate the need for considering habitat requirements of individual species and how habitat suitability changes over time when trying to assess the causes of their long-term population trends. The results also imply that any conclusions about the effects of other factors affecting forest bird abundances, such as increased nest predation or brood parasitism associated with habitat fragmentation, must also account for successional changes that may be affecting habitat suitability.

Latitudinal diversity patterns in estuarine tidal flats: indications of a global cline

Latitudinal diversity gradients are a general feature of the terrestrial realm. Fewer studies have addressed marine habitats and those concerning soft sediments have not reported such consistent trends. This study investigates global patterns of macroinvertebrate α‐diversity in estuarine tidal flats. A literature search was conducted to collect data on species diversity as well as various physical, chemical and biological factors that may prove useful in investigating the cause of trends. Regression analysis revealed a significant association between latitude and diversity expressed as Simpson's index of concentration (r2=0.44), the index being lower (i.e. diversity higher) at low latitudes. There was no significant association between diversity and either available estuary area or annual rainfall. A significant, although weak, relationship between diversity and mean annual temperature was apparent (r2=0.23), together with an increase in species to family ratio in the hottest areas. This could suggest greater evolutionary speed in the tropics (due to temperature increasing mutation rates and generation times) and may provide an explanation for the trend. However, a greater amount of variation is explained by latitude alone and it is suggested that a primary cause of the latitudinal cline in estuarine diversity may be the greater effective evolutionary time available for communities in the tropics, temperate estuaries being regularly disturbed by glaciation during the last 1.8 million years.

Latitudinal diversity patterns in estuarine tidal flats: indications of a global cline

Latitudinal diversity gradients are a general feature of the terrestrial realm. Fewer studies have addressed marine habitats and those concerning soft sediments have not reported such consistent trends. This study investigates global patterns of macroinvertebrate α-diversity in estuarine tidal flats. A literature search was conducted to collect data on species diversity as well as various physical, chemical and biological factors that may prove useful in investigating the cause of trends. Regression analysis revealed a significant association between latitude and diversity expressed as Simpson's index of concentration (r 2 = 0.44), the index being lower (i.e. diversity higher) at low latitudes. There was no significant association between diversity and either available estuary area or annual rainfall. A significant, although weak, relationship between diversity and mean annual temperature was apparent (r 2 = 0.23), together with an increase in species to family ratio in the hottest areas. This could suggest greater evolutionary speed in the tropics (due to temperature increasing mutation rates and generation times) and may provide an explanation for the trend. However, a greater amount of variation is explained by latitude alone and it is suggested that a primary cause of the latitudinal dine in estuarine diversity may be the greater effective evolutionary time available for communities in the tropics, temperate estuaries being regularly disturbed by glaciation during the last 1.8 million years.

The Ties That Bind: Perspectives on Marriage and Cohabitation

Ties That Bindwas organized to review and assess the scientific evidence about the causes of trends in marriage and other forms of intimate unions. The contributors address these two questions: What do we know about the factors that influence the formation of marriages and other intimate unions, the timing of union formation, and the forms that unions take? What factors explain the dramatic changes in union formation we have observed over recent decades? Edited by Linda J. Waite. Co-edited by Christine Bachrach, Michelle Hindin, Elizabeth Thomson, and Arland Thornton.

TRENDS IN THE CAUSES AND OUTCOME OF LIVER CIRRHOSIS DIAGNOSED BY LAPAROSCOPY IN OSAKA, JAPAN DURING THE PAST THREE DECADES

Background: Although various factors are assumed to have substantially altered the demographic characteristics of liver cirrhosis, few studies of patients with endoscopically confirmed cirrhosis have been done in Japan. We analyzed trends in causes and outcome of liver cirrhosis in Osaka, Japan during the past three decades.Method: The study group comprised 466 patients with cirrhosis of the liver who underwent laparoscopy at any time between 1969 and 1998. To analyze trends in the causes and outcome of cirrhosis, the study period was divided into three 10‐year intervals, variables included hepatitis B surface antigen (HBsAg), hepatitis C virus (HCV) antibody, alcohol intake, causes of death and outcome.Results: Hepatitis C virus has remained the major cause of liver cirrhosis during the past 30 years. Hepatitis B virus has remained the cause of liver cirrhosis in about 20–25% in all three decades. Alcohol played a part in the development of liver cirrhosis in more than 30% of the study group, alone or with hepatitis viruses. Therefore, alcohol remains an important factor in the pathogenesis of cirrhosis. The outcome of cirrhosis has improved gradually during the past decade owing to more effective means of treatment for complications of cirrhosis.Conclusion: Hepatitis C virus has remained the major cause of liver cirrhosis for the past three decades. Improvement of outcome in patients with cirrhosis caused by HCV infection should be an important task in the next decade.